Talky but engaging oddity with a caveman going on a killing spree. Good make up for the deformed beast. The chiaroscuro lighting, the dark backgrounds and hard lighting on the subjects gives them a special highlight within the shot and becomes borderline expressionistic at times. The framing and composition becomes particularly expressive during key moments and adds to the strange atmosphere the film creates, especially during the last 20 minutes. The directing is mostly the typical static master shots with a few inserts but sometimes the director focuses on objects and even zooms in and out of them at certain moments for accentuation (not with the same end and narrative focus as, let's say, Jess Franco but still very good direction), unorthodox techniques that were rather underused in movies at the time it was made. This type of outsider art is why low budget regional movies are always far more interesting than the mass produced corporate productions from big studios, even to this day.
The ironic thing about this is that this movie about a strange being from a bygone era becoming unearthed and destroyed by the modern man suffered the same fate as its monster, being uncovered and taken from 1965 to 1981, only to be eviscerated by critics and audiences, who judged it negatively as soon as it was discovered. With the addition of gore and the fact that it seems like a throwback to the type of movie being produced just a few years earlier, perhaps it was a cute homage to 50's creature features. Either way, an unexpected but welcomed addition to the monster movie genre.